How to Install an Air Duct in a Suspended Drywall Ceiling – Part 2

How to Install an Air Duct in a Suspended Drywall Ceiling photo tutorial. Mount the new vent boot, install the branch duct takeoff and flexible air duct. This project is continued from Part 1.

Mount the Vent Boot in the Drywall Ceiling

The new Speedi-Boot™ 6″ air vent is set in the drywall ceiling cutout, ready to be fastened to the steel suspended ceiling runners with sheet metal screws.

Speedi-Boot Air Vent in Drywall Ceiling

Speedi-Boot Telescoping Arm Attachment

The Speedi-Boot air vent features adjustable telescoping arms that extend for a perfect fit. The arms have factory-installed nails for nailing to wood studs or trusses, however nails won’t work with the steel ceiling runners. Instead, I will fasten the arms to the steel runners with 1/2″ sheet metal screws using the factory-made pilot holes. Simple!

Speedi-Boot Installation with Sheet Metal Screws

Each of the four arms are secured to the steel runners with a single sheet metal screw. Here’s a close-up of how the telescoping arm is fastened with a 1/2″ sheet metal screw to the suspended ceiling steel runner.

Speedi-Boot Telescoping Arm Installation with Sheet Metal Screws

Install the Flexible Air Duct Branch Line

Slip the inner core of the 6″ flexible air duct over the Speedi-Boot collar and secure with metal foil tape, smoothing the tape for an air tight seal. The 90° vent boot is ideal for situations like this where there’s no insulation, making for direct alignment with the flexible duct to avoid kinks.

Speedi-Boot Flexible Air Duct Connection

Slide the flexible duct insulated outer jacket over the Speedi-Boot and secure with a 36″ long zip tie.

Vent Boot: Flexible Duct Outer Jacket and Zip Tie

You can find the 36″ HVAC ductwork zip ties in the vent and duct supply section of most home improvement stores.

Duct Board Take-Off for Flexible Duct

A 6″ inch starting collar is installed for the new take-off in the rigid duct board trunk duct. For details of how to cut the hole and attach the starting collar, see this related project.

Flexible Duct Start Collar in the Rigid Duct Board Trunk

The 6″ flexible duct is cut to length and attached to the starting collar with metal foil tape and a zip tie in as was done for the Speedi-Boot air vent.

Flexible Duct Connection to the Trunk Air Duct

View of the 6″ flexible duct routed through the ceiling crawlspace to the Speedi-Boot air vent. Take care to support to flexible duct with wide nylon duct straps and avoid sagging, pinches or kinks that would restrict the air flow.

Flexible Duct Routed through the Ceiling Crawlspace

Overhead view of the new 6″ flexible air duct takeoff from the rigid trunkline ductwork. Notice the 1-3/4″ nylon web duct hanger strap supporting the air duct between the 2×4 wall studs.

Flexible Air Duct Branch from the Trunk Duct

Flexible duct must be supported with hanger straps at least every 5 feet in suspended installations.

Speedi-Grille™ Ceiling Register Installation

I’m back to the main room in the finished basement to install the ceiling register. Speedi-Boots feature a cardboard dust cover to keep out dirt and paint.

Speedi-Boot Air Vent Dust Cover

Remove the dust cover to reveal a pristine air vent.

Speedi-Boot Air Vent Drywall Ceiling Installation

Speedi-Boot accepts any standard ceiling register, but I’ll be using the Speedi-Grille™ companion product which features mounting tabs on the back for snap-in hands-free installation. The Speedi-Grille simply snaps into the steel opening of the Speedi-Grille vent boot. This is great because I now have two free hands to install the permanent mounting screws without worrying about the grill falling on my head, dropping a screw or my DeWALT drill/driver, and extra trips up/down the ladder.

Speedi-Grille Ceiling/Wall Register – Hands Free Installation!

The Speedi-Grill is permanently mounted with the included screws:

Speedi-Grille Air Register – Ceiling Mount

View of the completed Speedi-Boot and Speedi-Grille air vent installation in the basement ceiling. The air flow from the new vent can be felt in the middle of the room – nice! The basement should be a lot more conformable this winter.

Speedi-Boot and Speedi-Grill: Drywall Ceiling Mount

Speedi-Boot’s unique telescoping arms and screw attachment option made it easy to locate the air vent in the suspended drywall ceiling, where a installing a raw vent boot would be a real challenge.

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6 Comments

Hi. Looks good. But you didn’t show how the vent was screwed into the drywall/sheetrock. It looks as if the screws are affixed directly to the drywall? Or did you use some form of mounting bracket or drywall anchor? It’s not evident from the images. Thanks.

The vent register mounting screws will pull and compress the rubber gasket against the back of the drywall.

The vent boot does have four pilot holes in the corners for mounting to the bottom (crawlspace side) of floor decking. The difference between floor decking and drywall installations are: * Drywall holds screws very poorly unless drywall screw anchors are installed. Most drywall anchors are designed to penetrate the drywall, which would be unsightly and the protrusions many prevent the vent register from lying flush against the finished drywall. * Floor vent registers are usually the “drop in” type held in place by gravity, as opposed to wall and ceiling vents which have face mounting screws.

Hello, I recently got my home built, and I moved in right as summer was over (so this is the first summer that I used the AC)… well its considerably warmer on the 2nd floor than it is in the basement and on the first floor. The basement was finished afterwards by a different contractor, they are saying that the contractor must have done something off in the basement (he installed a duct in the main living area and in the bedroom, as well as a return in the living area) I did feel air coming out of the return, should that be? what are your thoughts?

Sounds like the other contractor who finished the basement messed up your duct work and air flow balance.

> I did feel air coming out of the return, should that be? No way!! Returns are air intakes that deliver air from the room back to the air handler.

> what are your thoughts? Pinpointing the problem is difficult without seeing the basement ductwork modifications. My guess is the basement contractor connected the new duct to the main living area at a bad location in the supply plenum or trunk duct which greatly imbalanced the air flow and is starving the 2nd floor of supply air. The air blowing out of the basement return duct suggests he may have blocked the supply air duct which is causing havoc with your air handler blower motor and system efficiency. Again this is just a guess.

See my comment here for ductwork design references to get a better idea of what properly designed and installed ductwork should look like.

I’d call an HVAC service company, explain the ductwork issues and ask them to investigate. The AC tech will probably find what’s wrong right away.

I’m a new homeowner and very novice with everything but learning as I go. I was running speaker wire for my surround sound above my drop ceiling in my basement. A small problem occurred when I got caught up under the A/C duct. I tried to gently push it up for some extra space but then the register 2 tiles over fell out. I’m guessing the previous homeowner did a poor job securing it because it looked like it was barely hanging on to begin with. Also, the vent is sort of free floating in there with no cross T between the tile grids.

I purchased a new tile from Home Depot and now I have to cut the opening, match it to the vent, and mount the register. Any tips on how to go about doing that the simplest way?